Industrial Fire Journal - Fire & Rescue - Hemming Group Ltd
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Made-to-measure foams
Published:  01 October, 2008

The chemists at Hamburg-based company Dr Sthamer have been developing speciality foams for specific risks for a long time, explains Jan Knappert (International Sales Director), which is why the organisation has developed a clear idea of the type of information required to develop a specification that fully meets the requirements specified.

At the foundation of the development of any new foam, explains Jan Knappert, are the 17 following parameters:


• Fuel source
• Risk to be protected
• Method of application, ie fixed system or monitor, gentle or forceful application
• Development time scale
• Development cost
• Available in-house chemical/technical resource
• Expected annual volumes, ROI potential
• Preferred induction ratio
• Freeze protection
• Drainage time
• Viscosity
• Health and environmental compatibility
• Environmental impact BOD, COD etc
• Third party approvals EN, UL, IMO etc
• Ingredients permitted or excluded ie fluorines, chlorines , glycols etc
• Client water supply: does the foam need to work with fresh water, seawater, brackish water, treated industrial water, or firewater runoff?
• Future development potential of the product: do additional features need to be built in during initial development?

Once these questions have been answered, and a general specification developed, Dr Sthamer allocates a number of chemists to the project. “We acquire samples of the fuel – or risk – as well as take delivery of the hardware foam-making equipment,” explains Jan Knappert. “Next we test to see whether one of our standard products nearly fits the bill, or whether enhancing is required.”


Naturally if an existing formulation can be enhanced, then the process is greatly shortened. “If we can optimise an existing formulation the process can be fast, with a few weeks to develop and test, followed by around four weeks for third party verification.”


Chief Scientist Dr Prall adds that, as in all R&D, strict timing is not possible and even if the perfect foam is hit upon at the first try, the process takes around three months from development request to officially approved product. “But you never hit it with the first try – we normally have four to six months of development.”


Hitting on the right combination of ingredients is a long process of continually testing reactions of key ingredients with sample fuels, explains Dr Prall. “We start with the product that is the nearest to the goal, and then we think of what we can alter to get the preferred values.”


The problem is that altering one property of the foam concentrate has knock-on effects. “If you perhaps want to lower the freezing point,” points out Dr Prall, “you also alter the density, the viscosity, the expansion ration and drainage time – as well as the extinguishing properties. To compensate that, you can add some other ingredient, but then again that alters all values as well as the freezing point.”


Adding anti-freezing agents such as MEG mono Ethylene Glycol can alter firefighting capabilities, adds Jan Knappert. “It is a balancing act of priorities! The chemist’s main job is to find the best all round solution to the client’s requirements.”


And things get really interesting when new raw materials are introduced, says Dr Prall. “First you have to choose a formulation where you want to try it in. Then you have to try different concentrations because more is not always better.” And it gets weirder. “You also have to try it with all other ingredients as there are often synergistic effects where one plus one does not equal two, but three or even four.”


When the formulation is hit upon, further testing takes place against stipulated standards, and then further testing takes place. “We then try to come up with a perfect product by altering all ingredients in the one or the other direction to see what happens. And when we think we have the perfect product, we have to go back to the drawing board because the raw materials turn out to be too expensive. So now we have to try to take out the expensive materials without screwing up the values.”


After all this, the result should be a finished and well-polished product that meets all the wishes of the customer. But that’s not to say the testing is finished, oh no.


“Foam samples then need to be submitted to the external independent accreditation bodies for extinguishing ability, burn back resistance, environmental acceptability ie BOD (biological oxygen demand) and COD (chemical oxygen demand), resistance to aging for long term storage, freeze protection, and the relevant hygiene institute then runs tests to confirm there is no detrimental impact on humans during use,” explains Jan Knappert.
Finally, the foam is then submitted for certification to the requirements of EN, UL, IMO etc, and the necessary documentation drawn up ready for sale.